Switch actuating mechanism



i H. W. G'RIKSCHEIT SWITCH ACTUATING MECHANISM April 22, 1952 Filed Nov.3, 1948 JNVENToR.

HEM? Y w GR//fsc/g/ BY 'April 22, 1952 H. W. GRIKSCHEIT SWITCH ACTUATINGMECHAN ISM Filed NOV. 3, 1948 2 SHEETS-SHEET 2 Patented Apr. 22, 1952UNITEDl STATES.

TNT GFFICE. i

SWITCH AcrUA'rING MEcnANIsM Henry W. Grikscheit, Detroit, Mich.

Application November 3, 1948, Serial No. 58,065

j Claims.

This` invention. relatesy to lim-it: switches and` stances where. limit,switches are employed. ThisgatherY with the man-ner in whichvariations;in`

the factors; of flexibility outlined above canbe incorporated by minormodifications from this specic construction., ofi-e- Figf. l, a plan,view of a limit switch; assembly with` the cover of the case thereofremoved;

Eig.,k 2:.. ar section in elevation taken along;Y the line-Zz--Zof Fig.v1 and showing; the cover in. place;

e Fis.3-,. an. elevation ofa portion; of the., lim-it switch. showing:the. actuating member. thereof er, a. section taken along: the. linevlie-4 of; Fier. 1:;

Fig. l5, a datan taken along the une 5,-5 Qf Fig. 2 and showing; theattachment between the actuating member and thel limit switch,V assembly;v Fig.v 6-,a. detail taken along the line-f 6-l of Fig.l l andshowing.the connection between an electrical switch element and the assembly.

Alllimit switch assemblies. contaim as common elemente an electricalswitching element and an.

actuating member for the vswitch assemblyy together with amechanism ofsome kindV Jto-prod-uce operation of the electrical: element upon moverlment ofthe actuating member. 'I'heelectrical element may-be considered`as a sub-assembly and is chosen according tothe particular electricalfunction'to be performed by theA switch.

These features arev also. found in the. present construction whichincludes two electrical switch elements Il, mounted within a suitablecase or housing l2, and an actuating member I3;y the Thesey drawingsconsist operation of the device. being suchl .that the; elec.`

tricalswitch elements llfunction in response to rotation of. theactuating member I3. Limit switches. are, used for a, wide variety ofpurposes; each of which. mayA require slight differences, in. theoperation of the switchinv order that it may,V

perform its intended function.. The-most frequent variations betweenswitchesconsist in. changnes, in;

operation caused by changing one or more. ofthe` variable factorspreviously enumerated. For ex;- ample, in a specific installation foralimit switch,l it may be necessary that thev electrical' switch elementbe; operated upon l,0 of rotation of.. the actuating memberand that;Such actuatiugmem.- ber-'then be able to move an, additional number: ofdegrees of overtravel. For a second installa-.- tion it may'v bedesirable to provide a switch which functions in the same manner but,Iwh h includesf a, different' number; of electrical switch instance, the,function of the. limit switchv may specifyl a; construction in which.one electrica-l element operates after a certain number off degrees ofmovement of the actuating; member while av Secondi element operates;after some additional: number of degrees, of movement.

Other possible variations include the return.' movement of the actuatingmember which.: inone case, may be automatic and,v invanothcr, manual.As: previously mentioned,v the principal object. o f the present.invention is to provide a limit switch actuating mechanism which,through-slightvarif. ations, caribe-modiiied to efiect any-ofthe for-,eegoing (manges,l the functieIii-Iig Of switch or-v any c.omloinationl ofsuch. changes..

Other objects: include the provision of an actu--A atingv mechanism;whichl is adaptable tcstandard commercial types of electrical switch`elements; the provision. of aA limit Aswitch wherein-the actu# ating`member can be. accurately adjusted. to, ther desired initial position;and the, provision of an` actuating, mechanism which will beparticularly resistant. to shock or, sudden impacts. against, the;

actuating member'. Other more specific objects,

side by side relation within the case and are separated from the bottomthereof by suitable spacing blocks I5 and I6 and held in position byscrews I1. The operating arm I3 is attached to a hub plate I8 which, inturn, is keyed to a collar I9 rotatable with a Shaft 28 which projectsoutwardly from the bottom of the case I2. That portion of the casesurrounding the shaft is formed as a bearing housing 2| and a pair ofball bearings 22 extend between this housing and the shaft to supportthe latter. The inner portion of the shaft is formed as a post 23 ofincreased diameter to provide a shoulder 24 which abuts against theinner race of the inner bearing 22. A circular cam plate 25 is firmlyattached to this post along an angular supporting surface 2E formed onthe inner end thereof so as to lie at an angle to the longitudinal axisof the shaft.

Extending between the pair of electrical switches II is a rocker arm ormain actuating member 21, one end of which is mounted between a yokeformed by a pair of vertical members 28 which are fabricated as part ofthe spacer block I5. A pivot pin 29 serves as a connection between therocker arm and the yoke members 28, and from this pivot pin the rockerarm extends between a U-shaped guide and stop 38. The free end of therocker arm is provided with a stub shaft 3| upon which a roller bearingfollower 32 is mounted so as to contact the underface of the cam plate25. Two notches 33 are cut in the underside of the rocker arm to definea projecting lug 34, which acts as a retaining member for one end of acompression spring 35, the other end of this spring being held within acircular recess 35 formed as part of the spacer block I6, so that thespring therefor urges the rocker arm 21 and its follower 32 upwardlyinto engagement with the underface of the cam plate 25. Upward movementof the rocker arm, however, is limited by the stop 30. In theconstruction illustrated, the cam plate 25 is provided with arectangular notch 39 which is engaged by the follower 32 of the rockerarm to define the normal or neutral position of the actuating member.

Actuation of the push buttons I4 of the electrical switches isaccomplished by a spring plate or switch actuating element 31, one endof which is held in position by being gripped between the spacer blockI5 and the bottom of the case. -A

stirrup member 38 is attached to the free end of this plate andstraddles the rocker arm 21 to provide a one-way connection between theplate and rocker arm. During upward or return movement of the rocker armtoward the neutral position shown in Fig. 2, its upper surface engagesthe cross-bar 42 of the stirrup member 38, causing upward movement ofthe plate 31 against the push buttons of the switch elements, depressingthem to a new contact position and at the same time producing tension inthe spring plate 31. Downward or actuating movement of the rocker armreleases this tension and is accordingly accompanied by downwardymovement of the spring plate. Since the switch element push buttons arenormally urged downwardly by their own spring means (not shown),movement of the spring plate downwardly is followed by downward movementof the push buttons until the switch contact elements reach a newposition.

In the initial installation of a limit switch assembly, it is frequentlynecessary to adjust the radial position of the operating arm I3 relativeto the shaft 28 for proper operation of the unit. A Vernier typeconstruction has been incorporated in the hub plate I8 and collar I9 forthis purpose, as is best shown in Figs. 2, 3 and 5, and consists of aseries of equally spaced holes 43 drilled in the outer face of thecollar I9. A second series of holes 44 are formed in the hub plate I8 ata radial distance from the center of the shaft 20 equal to that of theholes 43, there being a greater number by one of the holes 44 than oftheholes 43. For example, in the present construction, asillustrated inFig. 5, nine holes 44 are provided in the hub plate I8 while eight holes43 are spaced around the center of the collar I8. The hub plate is keyedto the collar by a washer 45 having a lug 4'6 adapted to be insertedwithin a hole 44 of the hub plate and to project into an aligned hole 43of the collar. A nut 41, engaging a threaded portion 48 of the shaft 20,holds the actuating arm on the shaft.

Studs 48, provided with nuts 50, project from one end of the case formounting the limit switch assembly, as to the member 5l, and a boss 52,equipped withinternal pipe threads, is located at the other end of thecase for the connection of an electrical conduit 53. The case isenclosed by a cover 54 and the electrical connections to the switchelements are segregated and insulated from the adjacent moving parts ofthe actuating mechanism by a U-shaped section of insulating material 55.

For operation of the switch, rotary movement of the operating arm I3 isinitiated in some extraneous manner. This rotation is accompanied by arotation of the shaft 20 and cam plate 25 and causes the follower 32 andthe free end of the rocker arm to be depressed against the force of thespring 35. The spring plate 31 has a normal direction of movement awayfrom the push buttons I4 and is held in contact with the push buttonsonly by the engagement between the stirrup 38 and upper surface of therocker arm 21. Downward movement of the rocker arm therefore isaccompanied by a downward movement of the spring plate 31 allowing thepush buttons I4 to move downwardly and place the contacts within theswitch elements in a new position. In the construction shown, the forceof the spring 35 has been correlated with the angle of the cam plate 25so that the upward pressure of the roller 32 against the underside ofthe cam plate will be sufficient to cause rotation of the latter andreturn the actuating member to normal position. -rIhis spring 35, ofcourse', must also be designed to have suii'icient strength to distortthe spring plate 31 during this returning movement.

It is to be noted that the combination of main actuating member 21,switch actuating member' 31 and stirrup 38 used to produce movement ofthe push buttons I4 effects a one-way connection between the actuatingmechanismv and the electrical switches with the result that movement ofthe main actuating member in an actuating direction is not limited tothe small amount of movement required by the push buttons. The notch 39in the cam plate has been made rather wide relative to the diameter ofthe follower 32, so that a large movement of the main actuating memberaccompanies a relatively small amount of initial rotation of theoperatingrar'm I3. The precise construction illustrated may, therefore,be said to have the following operational features. I

The electrical switches are very sensitive in responding to movement ofthe operating arm i3 and, in this respect, approximately 5 of rotationthereof causes sufficient downward movement of the rocker arm 2l toextend the push buttons and cause a change of electrical contacts withinthe switches. A large amount of overtravel of the operating arm ispermissible following this initial actuation, such overtravel in thisparticular construction being approximately 120. Operation of the twoelectrical switches is simultaneous and in this connection since no twoswitch units will be actuated by precisely the same amount of movementof their push buttons, a washer 40 of some suitable compressiblematerial (see Fig. 6) is interposed between the lower surface 4l of theswitch unit and the upper surface of thesupporting spacer block so thatthe vertical difference between the bottom of the case I2 and switchunit can be varied within the small limits necessary for this adjustmentby turning the screws I'I.

Modifications to the specific structure shown to vary the operatingcharacteristics of the switch assembly should be obvious to thoseskilled in the art, but will be briefly outlined. The amount of rotationof the operating arm required for operation of the switch elements canbe changed by design changes in the diameter of the follower 32 and/orthe width of the notch 39, or, if a large amount of rotation is desired,the notch can be eliminated and the cam plate made with a slope thatwill cause the proper form of operation. Overtravel of the operating armfollowing switch operation is also a function of the slope of the camplate.

Sequential operation of switch elements can be attained by positioningat different levels or by the use of multiple followers and associatedparts, and other changes would include the use of multiple notches onthe cam plate to give a number of actuations during a complete rotationof the actuating member.

The possibility of such minor changes is mentioned principally toillustrate the flexibility or adaptability of the invention, which isthought to constitute one of its more important features.

I claim:

1. A switch actuating mechanism for use in combination with amulti-position, push button operated switch element, comprising a switchactuating member mounted adjacent said switch element and adapted tocontact the push button thereof, said member being spring urged in a.

direction away from contact with said push button, a main actuatingmember, spring means associated therewith and urging said main actuatingmember in the opposite direction from the spring induced movement ofsaid switch actuating member, means to establish a one-way connectionbetween said members whereby said switch actuating member will be movedinto contact with said push button upon spring-urged movement of saidmain actuating member and means to control movement of said mainactuating member.

2. A switch actuating mechanism comprising a case, a shaft journaledtherein, an operating member attached to said shaft, a cam plate carriedby said shaft at an angle to the longitudinal axis thereof, a mainactuating member pivotally mounted within said case and having its freeend spaced from said shaft, spring means normally urging said free endof said main actuating member into contact with said cam plate, a switchactuating element positioned beneath said main actuating member andspring urged in a direction opposite to the spring-urged movement ofsaid main actuating member, means to establish a one-way connectionbetween said main actuating member and said switch actuating element,said spring means being capable of overl powering the spring-urgedmovement of said Switch actuating element, and a stop member positionedto limit the spring-urged movement of said main actuating member.

3. The invention set forth in claim 1 wherein the means to controlmovement of said main actuating member comprises a shaft, 'an operatingarm mounted thereon to rotate therewith, and a cam fixed to said shaft,said cam contacting said main actuating member and having a controlsurface adapted to cause movement of said main actuating member againstsaid spring means upon rotation of said operating arm.

4. A switch actuating mechanism comprising a case, a shaft journaledtherein, an operating member attached to said shaft, a cam plate carriedby said shaft, a main actuating member pivotally mounted within saidcase and spring urged into contact with said cam plate, a switchactuating element spring urged in a direction opposite to the springurged movement of said actuating member, a stirrup member carried bysaid switch actuating element and straddling said main actuating member,said stirrup being engaged by said main actuating member on spring urgedmovement thereof.

5. A switch actuating mechanism for use with a switch element of thetype wherein the switch contacts thereof are normally urged to oneposition and movable to a second position, comprising a movably mountedswitch actuating member normally urged in a direction of movementcorresponding to the normally urged direction of movement of said switchcontacts, a main actuating member spaced from said switch actuatingmember andlmounted for actuating and return movement, said actuatingmovement corresponding in direction to the normally urged direction ofmovement of said switch actuating member, one-way motion transmittingmeans interposed between said main actuating and switch actuatingmemberscomprising a stirrup connected to said switch actuating member andstraddling said main actuating member, said motion transmitting meansoperating to release said switch actuating member for the normally urgedmovement thereof during movement of said main actuating member in anactuating direction and to positively impart movement to said switchactuating member during return movement of said main actuating member,and means to produce actuating and return movement of said mainactuating member comprising a spring normally urging said main actuatingmember in a return direction of movement, and a control cam contactingsaid main actuating member and adapted to produce actuating movementthereof.

HENRY VJ. GRIKSCHEIT.

y REFERENCES CITED The following references are of record in the le ofthis patent:

'UNITED STATES PATENTS Number Name Date 2,328,266 Durbin Aug. 31, 19432,389,436 Kearney Nov. 20, 1945 2,460,695 Hennessy Feb. 1, 1949

